Most people think there isn't much that can be done with a solid axle to increase handling characteristics. There are dozens of variations and theories for suspension systems to plant it, but the housing itself-well it's just an archaic piece of technology that holds the axles and gears, right? That may be what sports car types who favor IFS would have you believe, but it's actually far from the truth. Remember, NASCAR still runs only solid axle rearends for both circle track and road race series, and trust us, those guys don't have just any old 9-inch in the rear.

2/25Much more than a 9-inch rearend, this housing holds secrets to track-day traction. Filip Trojanek of CorteX Racing created the 3-D model along with the spec sheet.

That's why we got in touch with Speedway Engineering in Sylmar, CA: to find out the best ways to increase lateral grip on a solid axle. Speedway Engineering has been building hot rod, and pro-level rearends for over 35 years and many big-name NASCAR teams trust them for precision, like Richard Childress Racing (RCR). Specs on NASCAR rearends are guarded like national security matters, and have to be precise enough to pass a laser-guided inspection.

So what's so special about these rearends? It's all about the camber and toe settings. Camber and toe in a rearend? Absolutely! Just as front tires entering a hard corner perform better with some static camber and toe, so do the rear tires, and those numbers have to be perfect; the tolerance is less than a .003-inch variance to meet Speedway's standards. Have you ever welded on a rearend housing? It's warped. We can't tell you how much, since every housing reacts differently, but we'll guarantee you that you've changed the factory settings significantly. As a matter of fact, rubbing your hand on one spot long enough on an axle tube can cause as much as 1/10th of a degree change. That's not much, but you get the idea. That means Speedway has to control warpage all the way through the build process to make sure customers and race teams get what they pay for.

3/25Speedway has a standard ordering form, but Filip Trojanek of CorteX Racing prefers to create his own spec sheets.

Though they have standard housing configurations, when you order a rearend from Speedway, it's essentially a custom-fabbed housing every time. The shop has a blend of high-end equipment and extremely experienced eyes that are hands-on with each housing. There's no automated welding here, just artists like Juan Alaniz, who lay a flawless bead. As shop foreman Frank Farell likes to say, "He can weld anything except a broken heart and the crack of dawn, but give him enough time and he could probably figure that out too." We believe it, just look at his work in the photos. Pure art.

There are a few proprietary points that we can't show you, such as exactly how Speedway dials in the negative camber and toe in their housings and the multiple stages of stress relieving that ensure that a housing's settings don't change during shipping.

This rearend isn't for every car. While the tires may love it in the corners, it's certainly not ideal for planting the tires for drag racing, and it will wear tires out a little faster, but no faster than a few track days. Nevertheless, if you've got bucks invested in your chassis and suspension and are looking for more grip through the corners, you couldn't possibly do better.